This repo is an example of an issue in the Jest test runner using multiple project configurations that define different moduleFileExtensions.
In some cases, we want to have code that is defined differently for a node.js environment than a browser/DOM environment. We do this to avoid needing to polyfill node.js's url module in the browser when we already have access to a powerful window.URL API in a browser (which is not available in node.js).
To do this, we set up our build environment to build server-side code with moduleFileExtensions to resolve *.node.js files before *.js files.
In Jest, we create two separate project configurations: config/jest/node.js and config/jest/web.js. These run the tests in the appropriate environment (node and jsdom, respectively).
This works great when you only include a module once in tests:
Command:
yarn jest -- src/__tests__/url.test.js --no-cache
Output:
yarn jest v0.27.5
$ "./jest-project-bleed/node_modules/.bin/jest" "src/__tests__/url.test.js"
PASS node src/__tests__/url.test.js
PASS web src/__tests__/url.test.js
Test Suites: 2 passed, 2 total
Tests: 8 passed, 8 total
Snapshots: 0 total
Time: 1.306s
Ran all test suites matching /src\/__tests__\/url.test.js/i in 2 projects.
Done in 2.19s.
However, if we have tests that reference the module that is split as *.js and *.node.js enough times (for this, I've used 3), we will see that Jest resolves the incorrect module once it has resolved it previously:
Command:
yarn jest -- --no-cache
Output:
yarn jest v0.27.5
$ "/Users/parmstrong/workspace/jest-project-bleed/node_modules/.bin/jest" "--no-cache"
PASS web src/__tests__/foo.test.js
PASS web src/__tests__/bar.test.js
PASS web src/__tests__/url.test.js
FAIL node src/__tests__/bar.test.js
● url.node › getUrlString › returns a URL string from host and pathname
ReferenceError: window is not defined
2 |
3 | export const getUrlString = (host, pathname, params) => {
> 4 | const url = new window.URL(host);
5 | url.pathname = pathname;
6 | url.search = params ? `?${stringify(params)}` : '';
7 | return url.toString();
at Object.getUrlString (src/url.js:4:13)
at Object.<anonymous> (src/__tests__/bar.test.js:6:18)
● url.node › getUrlString › returns a URL string with query params
ReferenceError: window is not defined
2 |
3 | export const getUrlString = (host, pathname, params) => {
> 4 | const url = new window.URL(host);
5 | url.pathname = pathname;
6 | url.search = params ? `?${stringify(params)}` : '';
7 | return url.toString();
at Object.getUrlString (src/url.js:4:13)
at Object.<anonymous> (src/__tests__/bar.test.js:10:18)
● url.node › getHostname › gets the host name from a string
ReferenceError: window is not defined
9 |
10 | export const getHostname = (url) => {
> 11 | return new window.URL(url).hostname;
12 | };
13 |
14 | export const replaceHostInString = (value, newHost) => {
at Object.getHostname (src/url.js:11:3)
at Object.<anonymous> (src/__tests__/bar.test.js:18:18)
● url.node › replaceHostInString › replaces the hostname in a URL string
ReferenceError: window is not defined
13 |
14 | export const replaceHostInString = (value, newHost) => {
> 15 | const url = new window.URL(value);
16 | url.hostname = newHost;
17 | return url.toString();
18 | };
at Object.replaceHostInString (src/url.js:15:13)
at Object.<anonymous> (src/__tests__/bar.test.js:25:18)
FAIL node src/__tests__/foo.test.js
● url.node › getUrlString › returns a URL string from host and pathname
ReferenceError: window is not defined
2 |
3 | export const getUrlString = (host, pathname, params) => {
> 4 | const url = new window.URL(host);
5 | url.pathname = pathname;
6 | url.search = params ? `?${stringify(params)}` : '';
7 | return url.toString();
at Object.getUrlString (src/url.js:4:13)
at Object.<anonymous> (src/__tests__/foo.test.js:6:18)
● url.node › getUrlString › returns a URL string with query params
ReferenceError: window is not defined
2 |
3 | export const getUrlString = (host, pathname, params) => {
> 4 | const url = new window.URL(host);
5 | url.pathname = pathname;
6 | url.search = params ? `?${stringify(params)}` : '';
7 | return url.toString();
at Object.getUrlString (src/url.js:4:13)
at Object.<anonymous> (src/__tests__/foo.test.js:10:18)
● url.node › getHostname › gets the host name from a string
ReferenceError: window is not defined
9 |
10 | export const getHostname = (url) => {
> 11 | return new window.URL(url).hostname;
12 | };
13 |
14 | export const replaceHostInString = (value, newHost) => {
at Object.getHostname (src/url.js:11:3)
at Object.<anonymous> (src/__tests__/foo.test.js:18:18)
● url.node › replaceHostInString › replaces the hostname in a URL string
ReferenceError: window is not defined
13 |
14 | export const replaceHostInString = (value, newHost) => {
> 15 | const url = new window.URL(value);
16 | url.hostname = newHost;
17 | return url.toString();
18 | };
at Object.replaceHostInString (src/url.js:15:13)
at Object.<anonymous> (src/__tests__/foo.test.js:25:18)
FAIL node src/__tests__/url.test.js
● url.node › getUrlString › returns a URL string from host and pathname
ReferenceError: window is not defined
2 |
3 | export const getUrlString = (host, pathname, params) => {
> 4 | const url = new window.URL(host);
5 | url.pathname = pathname;
6 | url.search = params ? `?${stringify(params)}` : '';
7 | return url.toString();
at Object.getUrlString (src/url.js:4:13)
at Object.<anonymous> (src/__tests__/url.test.js:6:18)
● url.node › getUrlString › returns a URL string with query params
ReferenceError: window is not defined
2 |
3 | export const getUrlString = (host, pathname, params) => {
> 4 | const url = new window.URL(host);
5 | url.pathname = pathname;
6 | url.search = params ? `?${stringify(params)}` : '';
7 | return url.toString();
at Object.getUrlString (src/url.js:4:13)
at Object.<anonymous> (src/__tests__/url.test.js:10:18)
● url.node › getHostname › gets the host name from a string
ReferenceError: window is not defined
9 |
10 | export const getHostname = (url) => {
> 11 | return new window.URL(url).hostname;
12 | };
13 |
14 | export const replaceHostInString = (value, newHost) => {
at Object.getHostname (src/url.js:11:3)
at Object.<anonymous> (src/__tests__/url.test.js:18:18)
● url.node › replaceHostInString › replaces the hostname in a URL string
ReferenceError: window is not defined
13 |
14 | export const replaceHostInString = (value, newHost) => {
> 15 | const url = new window.URL(value);
16 | url.hostname = newHost;
17 | return url.toString();
18 | };
at Object.replaceHostInString (src/url.js:15:13)
at Object.<anonymous> (src/__tests__/url.test.js:25:18)
Test Suites: 3 failed, 3 passed, 6 total
Tests: 12 failed, 12 passed, 24 total
Snapshots: 0 total
Time: 2.619s
Ran all test suites in 2 projects.
error Command failed with exit code 1.